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Biomedical subjects

R H Barnes

Publications and source records attributed to R H Barnes.

At least 37 records · Page 2Linked to original sources
PubMed1976

Maternal protein malnutrition during gestation alone and its effects on plasma insulin levels of the pregnant pig, its fetuses and the developing offspring.

The effects of restricting protein intake on plasma insulin were studied in pregnant pigs, fetuses and the developing offspring. Pregnant pigs were fed diets containing 18%, 3% or 0.5% protein throughout the gestation period. At 10, 13 and 15 weeks of gestation, fetuses were removed from the uterus after bleeding the dam. Plasma samples were used for insulin determination by a radioimmunoassay procedure. At week 15 of gestation, plasma insulin levels were significantly higher in pregnant pigs fed 18% protein and also in their fetuses than in the other two groups. There was a high correlation between fetal insulin level and fetal growth rate (r = 0.84). Two-day-pld pigs from another set of pregnant pigs fed the diet containing 18%, 3%, or 0.5% protein during gestation were cross-fostered to control nursing dams and weaned at 4 weeks of age to a standard diet. Plasma smaples obtained at regular intervals were used for insulin determination. Offspring of pigs fed 0.5% protein during gestation had consistently low insulin levels in postnatal life in spite of cross-fostering and standard feeding after weaning. It appears that one of the stimuli which control maternal insulin secretion and placenta transfer is the maternal protein intake while severe maternal protein restriction might contribute to the low levels of insulin in the progeny during postnatal life.

Animals↗
PubMed1976

Plasma insulin levels in weaned pigs fed protein or energy restricted diets.

Two experiments were conducted with pigs to investigate changes in plasma insulin levels during protein-energy malnutrition. Three or four week old pigs were fed a control diet (18% protein), an energy-restricted diet (19% protein) or a low protein diet (6% protein) for 8 weeks. Energy restriction was achieved by feeding the control diet in amounts that allowed some growth, but only to an extent equal to the low protein diet. At the end of the restriction period, all pigs were fed the control diet for another 8 weeks. Blood samples from the superior vena cava were collected at intervals throughout the experimental period. Plasma samples were analyzed for insulin by radioimmunoassay. Protein restriction after weaning resulted in persistently low insulin levels during depletion and rehabilitation periods, while high levels of plasma insulin were observed in energy-restricted pigs only during the depletion period compared to pigs fed the control diet.

Animals↗
PubMed1976

Decreased dietary protein or energy intake and plasma growth hormone levels of the pregnant pig, its fetuses and developing progeny.

The effects of low protein diets on plasma growth hormone were studied in pregnant pigs, fetuses and the developing progeny. Pregnant pigs were fed 18%, 3% or 0.5% protein diet throughout the gestation period. At 10, 13 and 15 week of gestation, fetuses were removed from the uterus after the dam had been bled to death. Plasma samples were used for growth hormone determinations. In a second experiment, 2-day old pigs from another set of pregnant pigs fed the diet containing 18%, 3% or 0.5% protein during gestation were cross-fostered to control nursing dams and weaned at 4 weeks of age to a standard diet. Plasma obtained at regular intervals was used for growth hormone determination. Plasma growth hormone was significantly higher in dams fed 0.5% protein after week 13 of gestation. High growth hormone (ten times the dam GH level) was observed in all fetuses irrespective of maternal dietary manipulation. Offspring of severely protein deprived pits (0.5% protein) had significantly elevated growth hormone levels up to 12 weeks of age in spite of cross fostering to a control dam after birth. The data suggest that there is little or no effect of maternal protein restriction on fetal growth hormone levels but the persistent high growth hormone levels in the progeny of severely malnourished pigs indicate a possible impairment of the production, release or catabolism of growth hormone and/or its releasing factor.

Animals↗
PubMed1976

Immunoreactive growth hormone levels in pigs fed protein or energy restricted diets during the postweaning period.

Developmental changes in growth hormone levels during protein or energy malnutrition was studied in weaned pigs. Three or 4 weeks old pigs from control dams were fed a control diet (18% protein), an energy-restricted diet (18% protein) or a low protein diet (6% protein) for 8 weeks. Energy restriction was achieved by feeding the control diet in amounts that allowed very little growth. After the restriction period, all pigs were fed the control diet ad libitum for another 8 weeks. Blood samples were collected at intervals throughout the experiment and the plasma was analyzed for growth hormone by radioimmunoassay. Post weaning protein deprivation resulted in higher growth hormone levels during the restriction period as compared to control pigs or pigs with a restricted energy intake.

Age Factors↗
PubMed1976

Plasma adrenocorticosteroid levels in protein and energy restricted pigs.

Pigs (Yorkshire) were subjected to protein-energy malnutrition in the following manner: 3- or 4-week-old pigs from control dams were fed a control diet (18% protein), an energy-restricted diet (18% protein), or a low protein diet (6% and 3% protein) for 8 weeks. Energy restriction was achieved by feeding the control diet in amounts that allowed some growth, but only to an extent equal to the low protein diet being matched. After the restriction period, all pigs were fed the control diet for another 8 weeks. Blood samples were collected at intervals from the superior vena cava. Plasma samples were analyzed for corticosteroids in all groups and for free cortisol in the controls and 3% protein groups. No significant differences were found for total plasma corticosteroids among all groups. Free cortisol was found significantly higher in the 3% group compared to the controls. An ACTH test was performed with depleted and recovered pigs of the 3% protein group and controls. No differences were found among controls, depleted and recovered pigs.

Adrenal Cortex↗
PubMed1975

Role of coprophagy in masking dietary deficiencies of cystine in the rat.

When a diet containing raw soybean was fed to rats, there was an increase in the synthesis of pancreatic protein, presumably exocrine protein, as evidenced by an increased uptake of [35S]cystine. There was also an increased transsulfuration of methionine sulfur as indicated by labeled sulfur transformation from methionine to cystine. This same pattern of events was produced in rats receiving a casein-containing diet when 50 mg of crystalline trypsin inhibitor was administered by gavage. However, if coprophagy was prevented, the increased uptake of [35S]cystine and [35S]methionine transsulfuration under both dietary conditions was blocked. It was found that prevention of coprophagy was without effect upon these two processes if supplementary dietary cystine was provided or if a dietary protein source with adequate cystine, i.e., heat-treated soybean, was provided. It was concluded that by practicing coprophagy, sufficient fecal cystine was being returned to the upper intestinal tract to permit some synthesis of pancreatic exocrine protein and with this stimulation of synthesis, transulfuration could proceed. This assumes that the biosynthesis of cystine is dependent upon the availability of sufficient cystine to permit active protein synthesis. In another situation where cystine requirement is high, namely, the rapidly growing rat, a limited amount of cystine was fed by providing a 12% casein diet. Either supplementary cystine or methionine was provided and it was found that both amino acids gave optimal growth in conventional rats, but when coprophagy was prevented, optimal growth was achieved only with the cystine-supplemented diet.

Animals↗
PubMed1975

Nutritional effects on heart acetylcholinesterase and butyrocholinesterase activity.

Male rat pups were undernourished in energy and protein by assigning them at birth to lactating dams receiving a low-protein diet (12% casein) to decrease the maternal milk supply. A normal diet (25% casein) was fed to the dams of control pups. On day 21 the pups were killed and hearts were removed and examined from both groups. Hearts from the undernourished animals weighed less and contained less DNA, RNA, and protein. The chemical indices of cell number (DNA) and cell size (wt/DNA) were reduced in the hearts from undernourished animals. Assays of the cardiac tissue for the activity of acetylcholinesterase and butyrocholinesterase indicated that undernutrition altered the activities of both enzymes, but in opposite directions. Protein-energy undernutrition resulted in an increase in acetylcholinesterase activity and a decrease in butyrocholinesterase activity. The specific activities of choline acetyltransferase and cholinesterase were unchanged. The total activity of both cholinesterase and butyrocholinesterase was reduced in the hearts of the undernourished animals. The data indicate that nutritional status can alter the activity of cardiac enzymes which have been associated with controlling the rate and rhythmic contractions of the heart.

Acetylcholinesterase↗
PubMed1975

Effect of postnatal malnutrition on plasma corticosteroid levels in male albino rats.

Basal morning plasma corticosteroid concentrations were significantly elevated in 11 and 21 day old male albino rats suckled by dams receiving a 12% casein diet when compared to control rats suckled by dams receiving a 25% casein diet. Rats which were either well-fed or malnourished during lactation then given a 9% casein after weaning had elevated corticosteroid levels and adrenal hypertrophy at 49 days of age. These changes may be related to altered adrenocortical responsivity found in adult rats malnourished in infancy.

Adrenal Cortex Hormones↗
PubMed1975

Postnatal stimulation: the effects on cholinergic enzyme activity in undernourished rats.

Rats were malnourished during the first 3 wk of life by feeding their lactating dams a low protein diet. Half of both control-fed and malnourished groups were "handled" daily during the suckling period. After 4 wk of postweaning dietary rehabilitation and individual caging they were killed and brain minus cerebellum taken for choline-acetyltransferase (ChAc) and acetylcholinesterase (AChE) determination on neuronal-rice or glial-rich cell fractions. Early postnatal malnutrition resulted in a decrease in ChAc activity in the neuronal-rich cell fraction of the non-handled rats, but no change in ChAc activity of this cell fraction was observed from rats that had been handled. This finding parallels the prior observation that malnutrition induces behavioral changes that continue after nutritional rehabilitation, but these behavioral abnormalities are minimized or abolished by handling.

Acetyltransferases↗
PubMed1975

Maternal malnutrition and the neonatal environment.

Altered behavioral development was observed in suckling rats from dams fed a low protein diet either during gestation or during the lactation period. Lactational malnutrition markedly depressed all behaviors displayed by the suckling young. These included litter fragmentation, pup climbing, rearing, feeding, and drinking behavior. Although less severe, pups from a dam fed a deficient diet during gestation displayed the same altered behavioral development. Moreover, small birth weight pups born from well-nourished dams also showed delayed behavioral development. Contact with pups was increased in dams who were malnourished during the lactation period or who were nursing pups from dams malnourished during the gestation period. Results support in part the hypothesis that malnourished early in life "functionally isolates" the developing animal from its immediate environment.

Animals↗